The emergence of the internet of things provides humans the possibility to control devices for home, office and commercial applications. In many of these applications the controllable device is controlled via a portable control device (e.g. a smartphone or a tablet pc). The controllable devices (e.g. a lamp, a thermostat, an HVAC system, etc.) can be controlled manually or automatically. A link between the control device and the controllable device is required. Once this link has been established, the user is able to send control commands to the controllable device. One of the issues that arises is that the user remains able to control the parameters of the controllable device as long as the user is connected to the controllable device, even though the control device may not be in the same room as the controllable device. Patent application U.S.20140106735 A1 discloses a solution to this issue by a method of determining the distance of a portable control device relative to a controllable device via one or more RF beacons. The proximity between the two devices is estimated and control of the device is provided if the devices are within a predetermined proximity. This method, however, requires a plurality of RF beacons distributed throughout the environment, resulting in a complex solution to the problem.
Patent application EP 2731371 A1 discloses a data transceiving system which includes a user terminal (e.g. a tablet pc) configured to detect a sound around the user terminal and a location during a period of time and transmit information regarding the detected sound and the detected location to an external apparatus (e.g. a remote server). The external apparatus is configured to receive the information regarding the detected sound and the detected location, determine a user group based on the received information regarding the detected sound and the detected location, and transceive data relevant to the user group with the user terminal. In this system, a plurality of sounds may be detected by a plurality of user terminal, which sounds, detected during the same time peri-od, may be compared to determine that the plurality of user terminals are part of the same user group.